Ca$^{2+}$-aktivierte Cl-Kanäle und Cl-Akkumulation in Sinneszellen der Ratte

Putzier, Ilva

Dissertation / PhD Thesis/Book

Ca$^{2+}$-aktivierte Cl-Kanäle und Cl-Akkumulation in Sinneszellen der Ratte

Putzier, I. (Corresponding author)FZJ*

2004
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Berichte des Forschungszentrums Jülich 4113, VIII, 137 S. (2004) = Köln, Univ., Diss., 2004

Please use a persistent id in citations: http://hdl.handle.net/2128/2570

Report No.: Juel-4113

Abstract: While inhibiting most neurons of the central nervous system (CNS), Cl${-}$-currents activate somatosensory neurons and olfactory sensory neurons (OSN). Both cell types show C${-}$-currents coupled to intracellular Ca$^{2+}$-signalling. The receptor current of OSN is mostly carried by a Ca$^{2+}$-acitvated Cl${-}$-current. While Ca$^{2+}$-activated Cl--currents have already been detected by electrophysiological means in a variety of cells, no coding gene has been identified yet. Only one family of proteins seem to show properties of Ca$^{2+}$-activated Cl${-}$-channels: the CLCA-proteins, which have been cloned from non-neuronal epithelia. We have now cloned the first neuronal clca-gene from olfactory epithelium, rclcal, which could be localized in neuronal cells of the olfactory epithelium only. This thesis deals with the hypothesis that rclcal codes for the Cat+-activated Cl${-}$-channel of the olfactory signal transduction cascade. rCLCA1-specific antibodies have been generated to characterize and compare the rCLCAl-protein with other CLCA-proteins. rCLCAI is a glycosylated 125 kDa membrane protein with four transmembrane domains. It is proteolytically cleaved into two 35 kDa and 97 kDa proteins. Both rCLCAI-fragments are slightly enriched in olfactory cilia in comparison with whole olfactory epithelium. This has been shown for all olfactory signalling cascade-proteins. However, on slices of olfactory epithelium rCLCAI-antibodies do not localize the protein in cilia but detect tightjunction structures. Functional expression of rCLCA1 shows, that it generates an enhanced Cl${-}$-conductance in rclcal-transfected cells which has completely different properties than the native Cl${-}$-current of OSN. By examining rCLCA1 in Odora cells, an OSN-cell lineage, it could be proved that rclcal can not code for the Cat+-activated Cl${-}$-channel in OSN : Although Odora cells showed large Ca$^{2+}$-acitvated Cl${-}$-currents with properties of the native current, the rclcaI -gene and its protein could not be detected in these cells. Ca$^{2+}$-activated Cl${-}$-currents do depolarize somatosensory neurons and OSN, because these neurons have an outstandingly high [Cl]$_{i}$ compared with most CNS-neurons. In this thesis the [Cl]$_{i}$ of freshly dissociated somatosensory neurons has been measured by fluorescencelifetime imaging (FLIM) for the first time. The [Cl]$_{i}$ was 30 MM, thus Cl${-}$ currents can indeed activate somatosensory neurons. The [Cl]$_{i}$ is determined by the expression of different chloride-transport molecules, like the cation/Cl${-}$-cotransporter (CCC) proteins. This thesis shows that both OSN and somatosensory neurons do not express KCC2, the CCC-molecule that leads Cl${-}$ out of most neurons. In addition to this both types of neurons do not express NKCCL The Cl${-}$-accumulation process could not be elucidated by this thesis but an active Cl${-}$-accumulation process will be discussed.

Note: Record converted from VDB: 12.11.2012
Note: Köln, Univ., Diss., 2004

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